At least six Palestinians were injured in a separate protest in the West Bank

Golan Heights (CNN) -- Israeli troops fired on protesters trying to cross the fortified border between Syria and the occupied Golan Heights on Sunday, with Syrian authorities reporting more than a dozen dead and hundreds wounded.

The protests came on the anniversary of the 1967 Middle East War, when Israel captured the Golan Heights from Syria. The Israel Defense Forces did not immediately confirm any casualties, though a spokeswoman said that Israeli troops used tear gas and live ammunition on members of an "angered mob."

"We warned them verbally (and) with warning shots into the air," Lt. Col. Avital Leibovich told CNN. "And when these two options failed, we had to open fire selectively into the area, and this actually stopped those Syrians from reaching the Israeli-Syrian fence."

The Syrian state news agency said 23 people were killed and more than 350 wounded in the protests, which continued past nightfall. Medics could be seen carrying the wounded to vehicles and driving them away from the border.

A spokesman for U.N. Secretary General Ban Ki-moon condemned the violence and urged restraint.

"The events of today and of 15 May on the Golan put the long-held cease-fire in jeopardy. The Secretary-General calls for maximum restraint on all sides and strict observance of international humanitarian law to ensure protection of civilians," he said.

As many as 500 people took part in the demonstration, holding mid-day prayers on the Syrian side of the border, then crouching down behind ramparts that Israel constructed in response to similar demonstrations three weeks ago. The number later dropped to about 50, with protesters waving Palestinian and Syrian flags.

Clashes also broke out between Palestinians and Israelis at the Qalandia crossing between Jerusalem and Ramallah in the West Bank on Sunday. At least six Palestinians were injured there, one seriously, by rubber bullets. Israeli forces also fired tear gas, while Palestinians threw stones.

The clashes come three weeks after similar demonstrations marking the 1948 birth of the Jewish state -- a day of mourning for Palestinians, more than 700,000 of whom were displaced from their homes during the fighting that followed. Those protests left at least 12 dead.

Leibovich accused Syria of trying to use the protests to create a diversion "from the bloodshed that is taking place inside Syria," where the United Nations says a crackdown against anti-government protests has left more than 1,000 dead.

"There is no question about it," she said. "The policemen, the armed Syrian forces are looking back and not doing anything."

Demonstrators arrived in at least eight buses before the protest began, then came down from a hill known locally as "Shouting Hill" -- where people shout to family and friends on the other side of the border -- toward the ramparts Israeli forces constructed last month.

Leibovich said Israeli troops were better prepared to deal with the demonstrations than with the May 15 protests, beefing up forces along the frontier and making clear "that we would not tolerate any infiltration into the Israeli side."